Divide frosting in half. Use half of the frosting to spread a thin layer on cupcakes. Tint remaining frosting black with 1/2 teaspoon black food color. Spoon frosting into small resealable plastic bag. Snip a small corner from bag. Pipe frosting in the shape of a widow’s peak for the vampire’s head. Pipe a line of frosting for the mouth. Use jelly beans for the eyes and gummy candies, cut into triangles, for the fangs.